Generally, the above driving support device acquires, from an in-vehicle sensor such as an in-vehicle radar, a relative state, to a host vehicle, of an object which is present in a travelling direction of a vehicle and which requires a deceleration control of the vehicle. The object is a parking vehicle, a leading vehicle, or an oncoming vehicle, for example. Based on the acquired relative relationship between the object and the host vehicle, a driving support such as an alarm tone or intervention braking is performed.
Conventionally, there has been known a device described in Patent Document 1 as an example of the driving support device. A rear-end collision alarming device described in Patent Document 1 includes: alarm generation means that generates an alarm when a time-to-collision of a host vehicle with a leading vehicle is a threshold or less; leading vehicle lane-changing determination means that determines whether or not the leading vehicle changes lanes; and timing adjusting means that delays a timing of the alarm to be generated by the alarm generation means when it is determined that the leading vehicle changes lanes. The leading vehicle lane-changing determination portion finds an acceleration of the host vehicle and an overlap ratio indicative of a ratio of how much the host vehicle and the leading vehicle overlap with each other in a vehicle width direction, and then determines, based on the values thus found and thresholds, whether or not the leading vehicle changes lanes. When the overlap ratio is the threshold or less and the acceleration of the host vehicle is the threshold or more, the timing adjusting means adjusts a value of a threshold to be compared with the time-to-collision so that the value is smaller than a normal value. The reason is as follows. When the overlap ratio is the threshold or less and the acceleration of the host vehicle is the threshold or more, a driver intentionally approaches the leading vehicle so that the host vehicle overtakes the leading vehicle that changes a lane to an adjacent lane, so that the risk of collision is lower than a case of approach of normal driving and the timing to generate an alarm can be delayed.
As such, by performing the adjustment to delay the timing to generate an alarm based on a low possibility of collision, unnecessary generation of an alarm can be reduced and uncomfortable feeling of the driver can be reduced.